New varistor material

Abstract

A composite varistor material containing silicon carbide, a conductor, and an insulator has been developed. The material has rubberlike flexibility and is easily formed. A higher leakage resistivity (∼1012 Ω cm) and greater nonlinearity (∼10) than for silicon carbide varistors permit the material to be used as a gapless surge suppressor. The breakdown voltage (1–10 kV/cm) and other properties of the material vary with composition. High current capability (>200 A/cm2) and good energy absorption (>40 J/cm3) are obtained. Also, the material exhibits a low-temperature coefficient (∼4×10−3/K) and a low dielectric constant (∼10) with no observed loss peak.